The present invention relates to an airport surveillance system. An airport surveillance system of this kind is proposed in German Patent Specification DE-OS P 29 34 844 and the corresponding U.S. Pat. No. 4,179,695.
In the airport surveillance system described there, SSR interrogation signals (SSR=secondary surveillance radar, secondary radar) are transmitted to SSR transponders on vehicles, such as aircraft moving on the surface of the airport, which respond with an SSR reply signal if the vehicle is within the range of the interrogation signals. For vehicle identification, the SSR reply signal contains a code assigned to the respective vehicle. A display device shows where each aircraft or vehicle is located. This aircraft surveillance system involves a great amount of technical complexity. Two interrogators located opposite each other on both sides of the runway are provided for generating the SSR interrogation pulses. Since the interrogators are controlled from a center by being addressed, expensive cabling is required on the airport. All interrogators are provided with receivers.